It is known that some types of vegetable seeds must be subjected to suitable preliminary treatments to make them edible or usable for cooking purposes.
Coffee, for example, is harvested in green beans that are first subjected to a roasting treatment, during which they are dried at a high temperature by means of a flow of hot air that is intended to cook them and at the same time to remove the skin covering the beans.
The roasted coffee beans are then suitably ground and reduced to powder, so that they can be used for preparing coffee-based products and beverages.
Industrial machines for roasting and grinding coffee also are known, and are an integral part of coffee roasting systems having very high hourly outputs.
In particular, such industrial machines for roasting coffee generally comprise a substantially cylindrical fixed case that houses a drum rotating around a horizontal axis and that is provided with an opening for introducing the product to be roasted and an additional opening for unloading the roasted product.
In the known equipment, the roasting process is carried out by means of a flow of hot air that passes through the drum from the bottom toward the top, thus exploiting the natural motion of hot air, or that is forced to pass through said drum in an axial direction or from the top toward the bottom.
Other machines for roasting coffee used in bars and restaurants also are known, and have reduced dimensions compared to industrial machines and a capacity of at least 2-5 kg. The operation of these machines is substantially similar to that of the industrial machines.
Retail stores sell packages of roasted and ground coffee, and also packages of whole roasted coffee beans.
The whole beans product obviously costs less than the ground product, but the final consumer must then grind the coffee beans before consumption.
To this end, home coffee grinders are known and widely used, and typically consist of small manual or automatic machines that, by means of blades, grind the coffee beans to the size desired by the consumer according to the intended use of the product.
On the other hand, the retail sale of green coffee beans, that is, non-roasted beans, is not common, since the roasting equipment currently known is not suitable or efficient for domestic use, that is, for processing small quantities of coffee beans.
In fact, if the quantity of coffee beans to be treated is much lower than the capacity of the equipment, energy consumption is very high compared to the hourly output, and the quality of the roasting process also suffers, since the beans may become roasted excessively and be nusable for consumption.
Therefore, individual consumers have no incentive to buy unroasted coffee beans, which would allow them to save more than 80% on the cost of the raw material, because retail consumers have no available equipment that is suitable for roasting the beans efficiently.